Cleaning out the drain

If the debris is clogging the evaporator drain then the best way to clear the clog is to insert a coat hanger form the outside. You should find the drain on the passenger side of the engine side of the fire wall, down low. It should be covered with a rubber elbow. Remove the rubber elbow and insert a coat hanger - you will need to bend the coat hanger to be able to slide it into the drain. Once you push the debris out of the way any water trapped inside will flow out. There is no way to actually remove the debris without removing and disassembling the heater box. If the drain continues to become clogged it may become necessary to remove the heater box for cleaning.